`7.` Five suspects have been arrested by the police.

`8.` He was ordered to take a long rest by the doctor. 

`-` take a rest: nghỉ ngơi

`9.` A dancing class was started last week.

`-` Chủ ngữ câu bị động là đại từ nhân xưng (I, you, we, they, he, she, it) `->` Chuyển sang câu bị động thì có thể ko cần dùng (by + O)

`10.` The accident was seen by Mr. Smith.

`-` Chủ ngữ số ít `->` Đi với tobe "was"

`11.` My briefcase has been taken.

`12.` Our written work was returned to us by the teacher.

`13.` The report has been finished by noon.

`14.` The little boy was bitten by the mad dog.

`15.` Giống câu `7`

`16.` Giống câu `8`

`-` Bị động thì QKD

`-` Cấu trúc: S + was/were + VpII + (by + O) + time.

`-` Bị động thì HTHT:

`-` Cấu trúc: S + have/has + VpII + (by + O) + time.

`-` BĐ :

`+` QKĐ : S + was / were + VpII ( by O )

`+` HTHT : S + have / has + been + VpII ( by O )

`7 , 9 - 15`. [ Đã làm ở câu 4728878 , tham khảo ]

`8 , 16`.He was ordered to take a long rest by the doctor

`\text{# TF}`